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June 3, 1952 

Filed AuE. 8, 1947 

G. SUNDBACK 
AUTOMATICALnY LOCKING ZIPPER 

2,599,078 

$ Sheets-Sheet i 



June 3, 1952 

Filed Aug. 8, 1947 

G. SUNDBACK 
AUTOMATICALLZ. LOCKING ZIFPER 

2,599,078 

5 Sheets-Sheet 2 

j..I-.a  OEideon ,.undadc 



June 3, 1952 

Filed Aug. 8, 1947 

G. SUNDBACK 
AUTOMATICALLY LOCKING ZIPPER 

2,599,078 

 Shee%s-Shee% S 

92 94 



Patented June 3, 1952 2,599,078 

UNITED STATES PATENT OFFICE 

2,599,078 
AUTOMATICALLY LOCKING ZIPPER 
Gideon Sundback, MeadviHe, Pa., assignor to 
Talon, Inc., Meadville, Fa., a corporation of 
Pennsylvania 
Application August 8, 1947, Serial No. 767,i26 
8 Claires. (CI. 24--205.14) 

1 
This invention relates to automatic lock zippers. 
Such zippers have a pair of stringers or rows of 
interlocking elements, collectively called chain, 
and a slider embracing the chain for opening and 
closing the zipper by movement in opposite 
rections along the chain. The slider is automati- 
cally locked to the chain against undesired open- 
ing movement but is freely movable to close the 
zipper.. This is accomplished by an automatic 
lock or pawl, normally pressed against the chain 
by a spring and shaped to prevent movement of 
the slider in the opening direction, but permit- 
ring dragging or ratcheting of the pawl over the 
chain whenever the slider moves in the closing 
direction. The slider has a small handle or pull 
tab by which it is moved in either direction, and 
the pull tab automatically lifts the pawl out of 
engagement with the chain whenever the pull is 
operated to open the zipper. 
While such zippers serve their intended pur- 
poses within certain inherent limitations, they 
bave several disadvantages. Since they depend 
upon the force of the spring to effect locking, a 
strong spring is required to lock them securely, 
and this constantly urges the pawl so firmly 
against the chain that it ratchets roughly over 
the interlocking elements whenever the zipper is 
closed. This is objectionably noisy, it makes the 
slider rough to operate, and the pawl wears on 
the interlocking elements, rapidly destroying its 
locking point and destroying the locking action 
of the slider. When such a lock is used on colored 
zippers, the locking point rapidiy destroys the 
enamel or chemical finish on the chain. On the 
other hand, if it is sought to eliminate these dis- 
advantaes by using a light spring, uncertainty 
and insecurity of locking result, and with some 
types of interlocking elements, positive locking is 
impossible. 
Another objection to previously known lock 
zippers is that whenever the pawl is holding the 
zipper locked against a strong opening force (pro- 
duced by trying to pull the stringers apart) it is 
difficult or impossible to unlock the slider and 
open the zipper by pulling the tab. This may 
occur, for example, in corsets. This difliculty is 
due to two conditions, first the required unlock- 
ing movement of the pawl is thœe direct opposite 
oî its locking movement in the saine path, and 
second the force by which an interlocking element 
bears on the pawl is substantially perpendicular 
to this path. Therefore when the force tending 
 open the zipper is grœeat, great friction is cre- 
ated which must be overcome in the unlocking 
movément. In addition, if the parts are rough, 

2 
or if burrs are present, it may be quite impossible 
to unlock the zipper by any force which the user 
can apply to the pull tab with the fingers. 
It is among the objects of the present invention 
5 to provide an improved form of lock slider in 
which certainty and security of locking are 
fected and in which ratcheting of the lock in 
closing the zipper is eliminated or greatly ,re- 
duced; to provide an improved lock slider which 
10 is instantly and positively locked upon the slight- 
est tendency toward undesired opening; to pro- 
vide an improved lock which can be unlocked 
readily and by slight force even when securely 
locked against great opening force, and more 
15 specificallY fo provide a locking member which is 
moved from locked position to unlocked position 
by a different movement and along a different 
path than from unlocked position to locked posi- 
tion; and te provide an improved lock which 
20 normally held in a neutral position from which 
it may be moved automatically either to fully 
unlocked position when the zipper is intentionally 
opened, or may be moved to fully locked position 
by the interlocking elements themselves whenever 
25 the zipper tends ix) open itself. 
I bave round that in some instances, while 
is desirable to accomplish these objects, it may not 
be desirable to have an absolutely positive lock, 
for in some uses of the zipper very great and 
30 normal unintentional opening force on the slider 
may destroy the zipper or the article ix) which 
is applied. In these instances it is desirable to 
bave a reliable lock having the characteristics of 
a positive lock against normal opening force, but 
85 having a safety release which unlocks the zipper 
when the opening force becomes great enough to 
cause damage. Accordingly it is another object 
of my invention ix) provide an improved slider 
design bY which I can control the point at which 
4O the slider will be released without damage, even 
to the extent of absolutely preventing release 
where this is desirable. 
It is a further object of my invention te provide 
a lock slider having the characteristics enumer- 
45 ated and which can readily and economically be 
manufactured. 
-Vn the accompanying drawings: 
Fig. 1 is a perspective view of one form of 
zipper embodying my invention; 
50 Fig. 2 is an enlarged section on the plane 
of Fig. 1 showing the slider lock in neutral posi- 
tion; 
Fig. 3 is a fragmentary section corresponding 
to Fig. . showing the slider fully locked; 
55 . Fig. 4 is a view correspondirg to Fig. 3 showing 



3 
the pawl in one fully unlocked position, the posi- 
tion it takes when the zipper is being closed; 
Fig. 5 is a view corresponding fo Fig. 3 showing 
the pawl in another fully unlocked position which 
it takes when the zipper is being opened by the 
pull tab; 
Fig. 6 shows the pawl in a third fully unlocked 
position, which it takes when released by an ex- 
cessive opening force; 
Fig. 7 is a section of the zipper taken on the 
line 7--7 of Fig. 3; 
Fig. 8 is a section corresponding to Fig. 3 show- 
ing a modified ïorm of the invention in the fully 
locked position; and 
Fig. 9 is a section corresponding to Fig. 2 show- 
ing a second modified form, the pawl being in 
the neutral position. 
Referring to Fig. 1, the chain of the zipper has 
a pair of stringers i6 each consisting of a beaded 
fabric tape 2! to the beaded edge 22 of which is 
Sëcued. a row of irïtêrlocking elements 23. A 
lidér 24 for 0pening ad closing the zipper has 
the usUaI Y-shaped chnnel or passage, the end 
of wtiich is indîcaed t -5 in' Fig. 2 and the 
ro'gs section of which is indicted at -5 in Fig. 7. 
-li pagsgge sur0unds the chain. The passage 
ï fbriied by an Upper plate 26 of the slider, a 
loWê plate 27 and a wedge 26. The slider, when 
meVed upward on the Chain, that is to the left 
as seen  in Fig. 1, progressively interlocks the two 
r6v of elemerïts to close the zipper, and when 
inved in the opposite direction, progressively 
dier/ggges the rows to open the zipper. The 
stidgr is moved in either direction along the 
ctiiri  bY a pull tab or handle 29, slidably se- 
cured fo the upper plate by an- èlongated bail or 
10op  and so çrranged tht it Can pull the 
-slideç .from èither end: As so far described the 
onstruction and operation Of the zipper are wel! 
Ilowrl. 
.]:n the stider exemplifying my invention, the 
upPer plate is provided with an opening 32 (Fig. 
2). A iock is housed under the loop 36 and ar- 
ranged so that it can project through ttïe Open- 
ing.32 into the channel -. Preferabty the upper 
plate bas two simflar openings 2- and  sep- 
araed by a shelf or bearing 38, as seen best in 
Fig.-. The locking member consists Of a cen- 
trgl shaft 4 from which depend a pair of legs 
g2, . projecting ito the openings. The shaft 
filÏs tie space between the shelf 3 and the cap 
or leop 3. It has an opposite pair of rounded 
faces 44- (Fig. 2) so that it functions as a round 
shaft, turning through a limited angle in the 
bearing formed by the Shel 33 and the rounded 
end  of a depression 4 in the cap. The shaft 
can also s!ide a!ong the shelf 38. The leg 42 
form's the active locking pawl, the les 4 serving 
te guide the shaft on its bearings and to prevent 
binding. The Side walls 46 (Fig. 7) and thè end 
waH 6 (Fig. 2) of the cap form a well which 
confines a spring 2 which bears against a fiat 
face 64 of the shaft, urging the shaft to the left 
against the concave face 4. The end of the 
sprflig may be so formfl and positioned that 
it normally holds the lock with the pawI in the 
angular position shown in Fig. 2, which is the 
nomal or neutral position of the lock. 
The pawl, in its neutral position, is inclined 
With respect to a line perpendicular fo the chan- 
nel-. The pawl is long enough to project slightly 
into the channel in this position, just enough 
for the point te contact an interlocking e!ement 
if the sliler moves in either direction. Whenever 
he i0k is in the neutral position, and the s!ider 

2»599078 
4 
tends to more in the opening direction without 
the control of the pull tab, the  first interlocking 
element which contacts the locking point swings 
the pawl to the left, rotating the shaft clock- 
5 wise about its conter and bringing the pawl into 
the position (shown in Fig. 3) perpendicular to 
the channel, causing the locking point to project 
further into the channel between the interlock- 
ing elements. In this position the pawl is 
lo stopped or held by the wall of the opening 3-, in 
which position the lock is held by the spring 
blocking passage of the interlocking elements 
through the slider, thus preventing movement of 
the sli.der to open the zipper. 
15 When it is desired to open the zipper, the pull 
tab - is pulled to the right as seen in Fig. 5. 
This slides the shaft 4} to the right, compress- 
ing the spring, and since the locking point 
is held by the interlocking element with which 
0 it is in contact, the lock rotates clockwise as 
belote, inclining the pawt in the opposite direc- 
tion to the line which is perpendicular to the 
r0wg of elements through the axis of the- shaft 
as shown in Fig. 5, far enough .to remove the 
2 lo-cking point from the path of the interlocking 
elements. This permits the slider to be slid to 
the right and thus to open the zipper. 
While the slider cannot be freely moved fo 
open the zipper except under control of the pu]l 
0 tab, as wfll be explained,-the s!ider can be freely 
moved to close the zipper. Whenever the slider 
tends to move to the left, as seen in the draw- 
ings, each interlocking element strikes against 
the back of the locking point and rotates the 
35 shaft  counterclockwise, compress.ing the 
spring very slightly and swinging the leg 2 into 
the inclined position shown in Fig. 4, in which 
the locking point slides over the interlocking 
elements and permits the slider to move in the 
40 closing direction. Since the spring bears against 
the fiat face  the only compression of the 
spring during this latter rotation is caused by 
the slight distance that the lower edge of this 
fiat face moves during rotation of the lock from 
45 the position of Fig. 2 to that of Fig. 4. This is 
a very slight am0unt and produces a very slight 
restoringforce on the lock, reducing to a mini- 
mum the dragging force of the locking point on 
the interlocking elements when the zipper is 
50 being closed, and preventing appreciable wear of 
the locking point. 
It will be observed that in moving into locked 
position the pawl is rotated clockwise about a 
fixed pivot remote from the channel, so that its 
55 points swings from right to left and in swinging 
carrîes itself ïarther into the channel, until 
stopped where it projects the maxîmum dstance 
into the channel. However, in moving fo 
locked position the pawl rotates clockwise about 
ç0 the interlocking elements and the formerly fixed 
pivot is moved laterally to pivot the lock about 
an interlocking element and swing the opposite 
end of the pawl from left to right, dragging the 
pawl out from between the elements. In so doing 
65 thepawl is inclined oiposite to the inclination in 
the neutral position. 
As this opposite inclination away from the per- 
pendicular increases, it becomes easier ïor e 
force of the interlocking element acting on the 
i0 locking point to force the locking Point out of 
the channel. This is important in unlocking the 
sI.ider when it is locked against a vint heavy 
forcê tending to pull the stringers apart. For, 
d.ue to the arrangement of the parts, thiS force 
? tending fo open the zipper assists the unlocking 



2,599,078 

action rather than opposes it, once the pawl has 
been started away from ifs perpendicular posi- 
tion. Thus in Fig. 3, if there is a strong open- 
ing force on the slider hot due fo the pull tab, 
the interlocking element in contact with the lock 
pushes hard to the left, bearing against the lock- 
ing point with a force whose direction is repre- 
sented by the vector 600 in Fig. 3. The shaft 400 
is held against movement away from the inter- 
locking elements by the cap -00. This causes the 
inclined face of the locking point 500 to urge the 
interlocking elment against the lower wall 
of the slider. The wall reacts against the element 
and causes if fo press against the lock in a di- 
rection perpendicular fo the wall 27, as repre- 
sented by the force vector 6|. The resultant of 
these vectors 600 and 00| is the resultant total force 
exerted by the interlocking element on the lock- 
ing point. This is represented by the vector 002 
which must be perpendicular fo the face of the 
locking point. The component 00| in this posi- 
tion of the lock is perpendicular fo the cap and 
is completely absorbed or opposed by the bottom 
wall of the depression 44 of the cap. The com- 
ponent 0000 is perpendicular fo the face of the 
opening 32 which stops the lock. Thus no move- 
ment is produced. However, as soon as the lock 
is moved by the pull tab slightly away from the 
perpendicular toward the position of Fig. 5, the 
component 6| assists in pushing the shaft fo the 
right a]ong the cap. Increase in the inclination 
of the leg increases the effectiveness of this com- 
ponent 6 | in sliding the shaft along the cap, thus 
the very force which he]d the lock against ifs 
stop can now tend fo slide the lock along the 
stop and a]ong the cap, and assist the pull tab 
in unlocking the slider. 
This condition makes if .possible fo provide a 
s]ider in which the lock is automatica]ly re- 
leased by being moved away from the positive 
stop by an excessive force tending to open the 
zipper without the control of the pull. This is 
useful, for example, wherever if is desired fo bave 
the zipper open without damaging itself af the 
occurrence of an opening force which would de- 
stroy the tape of the zipper or damage the ar- 
ticle fo which the article is applied. 
The comportent 600 is opposed by an equal forc.e 
63 effected bF the wall of the opening 32. This 
force is in the opposite direction fo the force 
and if occurs af the point 65 where the lock con- 
tacts the stop. If this point is hot in line with 
the force 600, as is indicated in Fig. 5, a couple 
will be set up tending to rotate the lock clock- 
wise toward the position of Fig. . Since as 
practical marrer, if ma: be desirable to have 
some clearance between the inner surface of the 
top wing and the top face of the interlocking 
element, there wi]l be some offsetting of the lines 
of the forces 600 and 63. Thus a couple will be 
set uP which tends fo move the lock from the 
fullF locked position fo unlocked .position. This 
couple is opposed bF the force of the spring 
acting ai a distance equal fo the perpendicular 
distance from the effective line of action ' of the 
spring fo the point of contact between the lock 
and the inter]ocking element. If the amount of 
th couple exceeds the moment of the sprin.g, the 
lock will be rotated clockwise into the position 
of Fig. 6 and thus be withdrawn from locking 
position. The moment of the couple, fo any 
given opening force on the slider can be reg- 
ulated within limits b: determining, the point 
of contact between tle lock and the Stop, and 
the moment of the spring can .be regulated b: 

6 
changing the force of the spring. Thus, the 
point at which the safety opening .of the zipper 
occurs can be determined when the s]ider is con- 
structed. 
5 In some applications of the invention if may be 
desirab]e fo have clearance between the slider 
and the interlocking elements and yet have a 
positive lock which will hot be released by any 
unintended opening force, however great. Such 
l0 a lock slider is il]ustrated in Fig. 8. This is con- 
 structed as previously described except that the 
lock has a locking surface 700 which engages a 
corresponding surface 72 on a relieved portion 
behind the stop ïormed by the opening 32. The 
]5 surface 72 is formed at an angle which will pre- 
vent its forming a point bearing for any part of 
the surface 700. Therefore any tendency of the 
interlocking element to rotate the pawl out 
the perpendicular position and into unlocked po- 
20 sition tends fo produce c]ockwise rotation about 
the edge of the opening 32 at 74. Such clock- 
wise rotation is prevented by the projecting sur- 
face 6 engaging the surface 72. Preferably the 
surface 700 is parallel fo the inclined face of the 
25 locking point 500 and inclined about 45 ° fo the 
axis of the pawl, and the surface 72 is inclined 
45 ° fo the rows of elements, so that 72 is par- 
allel fo the face of 56 when the paw] is per.pen- 
dicuiar fo the rows and in locking position. The 
30 surface 7{} does hot extend toward the inter- 
locking elements beyond the line, perpendicular 
fo the surface 72 and passing through the point 
of contact between the Pawl and an interlocking 
e]ement. Beyond this line the projection carry- 
35 ing the surface 700 is preferably rounded or re- 
lieved on a radius hot greater than the distance 
to the point of contact between the interlocking 
element and the pawl, so as hot fo bind when 
the pull tab tends fo unlock the slider after the 
40 manner indicated in Fig. 5. The lock swings 
clockwise about the interlocking element and the 
rounded point oî the Projection carrying the 
surface 00 clears the surface 
In Fig. 9 is illustrated a modified form of the 
45 invention in which the spring 52 holds a modified 
form of lock yieldingly 'against an inclined stop 
900. The locking pin 9 has a head 92 which has 
a fiat side adapted fo rest on the sloping surface 
900. The spring 52 is placed in a bore or recess 
5O and rests in an annular recess 
positiordng pin 95 on the head of the lock. The 
spring substantially fills the bore so as fo hold the 
head against the side of the bore, as well as 
against the inclined stop 900. Otherwise the lock 
• 55 of Fig. 9 operates like that of Figs. 2 fo 5, but the 
inclined stop tends fo hold the lock somewhat 
more positively in ifs neutral position whenever 
the slider is hot locked nor being either closed or 
opened by the pull. When the lock rotates fr0m 
60 neutral into locked position, if pivots about the 
fulcrum formed by the edge 96 of the incllned 
support, this fulcrum being in the line perpen- 
dicular fo the rows of elements which passes 
through the stop formed by the wall of the open- 
65 ing 32, insuring that when the lock reaches the 
stop, if wfll be perpendicular fo the rows of ele- 
ments and project the maximum distance into the 
passage. 
I claire as my invention: 
70 1. A zipper comprising in combination a pair 
of rows of interlocking elements,a slider, having 
a passage for the elements, the passage diverging 
atone end of the slider and being adapted when 
moved in one direction along the rows to inter-. 
.75 lock the rows to:c!ose the zipper and when rnoved 



2,599,078 

7 
in the opposite direction to disengage the rows 
fo open the zipper, a lock pivoted in the slider 
and having a locking end, resilient means nor- 
mally and yieldingly holding the lock in a position 
with its axis inclined in one direction away from 
a line perpendicular fo the rows and with its lock- 
ing end projecting into the path of the elements, 
a pivot shaft on the lock, a pivoting and sliding 
support for said shaft adapted to maintain the 
shaft a constant distance ïróm the passage, said 
resflïen means normally holding said pivot shaft 
on said pivoting and sliding support and the lock 
being rotatable on said support toward a position 
perpendicular fo the rows to project the locking 
end frther into the path of the elements in re- 
sponse to initial uncontrolled opening movement 
of the sliler, a stop between the ends of the lock 
for stopping the lock when substantially perpen- 
dicular fo the rows to prevent ïurther opening 
movement of the slider, and a second pivot on the 
lock for contacting the stop. 
2. A zpper comprising in combination a pair 
of rows of interlocking elements, a slider having 
a passage for the rows and adapted when moved 
in one direction along the rows to interlock the 
rows to close the zipper and when moved in the 
opposite direction fo disengage the rows to open 
the zipper, a lock in the slider having a locking 
point atone end and a pivot shaft at the other 
end, a pivoting and sliding support for the shaft 
adapted to maintain the shaït a constant distance 
from the passage, resilient means for yieldingly 
holding the pivot shaft on said support and 
the lock normally in a position inclined in one 
direction fo a line perpendicular fo the rows with 
the locking point projecting into the path of the 
elements, the lock beLg rotatable in one sense 
about the axis of the pivot shaït into a position 
perpendicular to the rows to project the locking 
point further into the path of the elements, and 
a stop for stopping the lock in said perpendicular 
position the zipper including means for rotating 
the lock in the same sense about the stop into a 
position inclined in the opposite direction to the 
perpendicutar to remove the locking Point from 
the path of the elements. 
3. A zipper comprising in combination a pair 
rows of interlocking elements, a slider having a 
passage for the elements, the passage diverging af 
one end of the slider and being adapted when 
moved in one direction along the rows to interlock 
the rows to close the zipper and when moved in 
the opposite direction to disengage the rows to 
open the zipper, a lock in the slider having a lock- 
ing end, the lock.being rotatably supported in the 
slider, resilient means yieldingly holding the lock 
normally positioned with its axis inclined away 
ïrom a line perpendicular fo the rows and pointing 
toward the rows and toward the convergent end 
of the passage and with the locking end project- 
ing into the path of the elements, the lock being 
rotatable from said inclined position toward said 
perpendicular line whereby the lock is adapted to 
be rotated to project the locking end farther into 
the path of the elements in response to initial 
uncontrolled opening movement of the slider a 
pivot on the lock between the ends of the lock, .a 
stop on the slider for the pivot for stopping the 
lock when substantially perpendicular to the rows 
to prevent further opening movement of the 
slider, tle lock being adapted to be rotated about 
the pivot on the stop by excessive force tending 
fo. move the slider .in the opening direction to 
iclin :the lock away from the perpendicular and 

8 
remove the locking end from the path of the 
elements. 
4. A zipper comprising in combination a pair 
of rows of interlocking elements, a slider having 
5 a passage for the elements the passage diverging 
at one end of the slider and being adapted when 
moved in one direction along the rows to interlock 
the rows fo close the zipper and when moved in 
the opposite direction to disengage the rows to 
open the zipper, a lock having a pivot mounted 
in the slider remote from the rows and having a 
locking end, resilient means yieldingly holding 
the lock normally positioned with its axis inclined 
away from a line perpendicular to the rows and 
pointing to the rows and fo the convergent end 
of the passage and with its locking end projecting 
into the path of the elements, the lock being 
rotatable in one sense about said pivot toward 
the perpendicular line fo project the locking end 
farther into the path of the elements in response 
to initial uncontrolled opening movement of the 
slider, a second pivot on the lock adjacent the 
rows and a stop on the slider adjacent the passage 
for stopping the second pivot when the lock is 
substantially perpendicu]ar fo the rows, the lock 
being rotatable in the saine sense about the second 
pivot on the stop by excessive force tending to 
more the slider in the opening direction fo incline 
the lock away from the perpendicular and to 
emove the locking end from the path of the 
elements. 
5. A zipper comprising in combination a pair 
of rows of interlocking elements, a slider having 
a passage for the elements, the passage diverging 
35 at one end of the slider and being adapted when 
moved in one direction along the rows to inter 
lock the rows to close the zipper and when moved 
in the opposite direction to disengage the rows to 
open the zipper, a lock in the slider having a 
40 lockirg end, resilient means Fieldingly holding 
the lock normally positioned with its axis inclined 
away from a line perpendicular fo the rows and 
pointing toward the rows and toward the con- 
vergent end of the passage and with its locking 
45 end projecting into the path of the elements, a 
pivot shaït on the lock, a pivoting and sliding 
support for the shaft adapted to maintain the 
shaft a constant distance ïrom the passage, said 
resilient means normally holding said pivot shaft 
50 on said support the lock being rotatable on said 
support from said inclined position toward said 
perpendicular line whereby the lock is adapted fo 
be rotated to project the locking end farther into 
the path of the elements in response to initial 
5 uncontrolled opening movement of the slider, a 
second pivot on the lock and a stop on the slider 
between the ends of the lock for stopping the 
pivot when the lock is substantially perpendicular 
fo the rows, the lock being rotatable and slidable 
60 on the second pivot on the stop in response to 
excessive force tending to more the slider in the 
opening direction for sliding the sh.aft along the 
support to incline the lock in the opposite direc- 
tion to the perpendicular and fo remove the lock- 
65 ing end from the path of the elements. 
6. A zipper comprisin in combination a pair 
of rows of interlocking elements, a slider having 
a passage for the elements and adapted when 
moved in one direction along the rows to inter- 
7O lock the rows to close the zipPer and when moved 
in the opposite direction to disengage the rows to 
open the zipper, .a lock in the slider having a 
- locking POint at one end and a pivot shaft at the 
other end, a pivoting and sliding support for the 
75 shaft in the slider adapted to maintain .the. shaït 

10 

15 

2O 

25 

3O 



9 
a constant distance from the passage, resflient 
means yieldingly holding the pivot shaft on said 
support with the lock in a position norrnally in- 
clined in one direction with respect fo a line per- 
pendicular fo the rows and having the locking 
point projecting into the path of the elements, 
the lock being rotatabIe in one sense about the 
pivot suppo]'t into .a position perpendicular fo the 
rows to project thelocking point farther into the 
path of the elernents, rneans on the s]ider for 
stopping the lock substantially perpendicular to 
the rows, the lock being rotatable in the_ sarne 
sense about the stopping means to a position 
inclined in the opposite direction to the per- 
pendicular fo remove the locking point from the 
path of the elements. 
VE. A zipper comprising in combination a pair 
of rows of interloc]dng elements, a slider having 
a passage for the elements, the passage diverging 
atone end of the slider and being adapted when 
rnoved in one direction along the rows to inter]ock 
the rows to close the zipper and when moved in 
the opposite direction along the rows fo disengage 
the rows fo open the zipper, a locking rnember in 
the slider resflient means yieldingly holding the 
locking member in a position norrnally incIined 
fo a line perpendicular to the rows and pointing 
toward the rows and toward the convergent end 
of the passage, a locking point on the locking 
member, a pivot on the locking member rernote 
from the passage, a pivoting and sliding support 
on the slider for said pivot, sai.d resilient rneans 
yieldingly holding said pivot on said support the 
locking member being rotatable in one direction 
about the pivot fo move the locking mernber to- 
ward said perpendicular line and fo rnove the 
Iocking point toward the center of the passage 
and between the inter]ocking elements, a bearing 
surface on the locking rnember adjacent the lock- 
ing point adapted fo contact an inter]ocking e]e- 
ment when the locking point is so placed between 
the interlocking elernents, a stop on the slider 
adapted fo contact the lock at a point spaced 
axially frorn said bearing surface when the lock 
is substantially perpendicutar to the rows whereby 
opening force on the slider sers up a couple on the 
lock between the bearing surface and the stop, 
said couple tending fo rotate .the lock in the op- 
posite direction away from said perpendicular 
line. 

10 
8. A zipper comprising in combination a pair 
of rows of interlocking elements, a slider having 
.a passage for the rows, the passage diverging af 
one end of the slider and being adapted when 
5 rnoved in one direction along the rows fo interlock 
the rows to open the zipper and when moved in 
the opposite direction along the rows fo disengage 
the rows fo open the zipper, a locking member 
on the slider having a locking end, resilient 
I0 rneans yieldingly holding said ]ocking mernber 
norma]ly positioned with its axis inclined away 
from a line perpendicular to the rows and point- 
ing toward the rows and toward the convergent 
end of the passage and with the locking end pro- 
i.5 jecting into the path of the elements, a pivot 
shaft on the locking mernber, a pivoting and slid- 
ing support fo]" said shaft adapted fo maintain 
the shaft a constant distance from the passage, 
said resilient means yie]dingly holding said pivot 
20 shaft on said support the locking rnernber being 
rotatab]e on said support toward said perpendicu- 
lar line to project the locking end farther into 
the path of the elements in response fo initial 
uncontrolled opening movement of the slider, a 
2.5 stop on the slider for stopping the lock when 
axis is substantially perpendicular fo the rows, 
the zipper including means for sliding and rotat- 
ing the shaft on the support to incline the lock 
in the opposite direction away from said per- 
30 pendicular line and thus to remove the locking 
end from the path of the elernents. 
GIDEON SUNDBACK. 

35 

4O 

45 

EFEENCES CITEK} 
The following references are of record in the 
fi!e of this patent: 
UNITED STATES PATENTS 

Number 
2,222,986 
2,271,141 
2,289,585 
2,301,792 

Number 
417,781 
512,643 

Naine Date 
Poux ............... Nov. 26, 1940 
Lange .............. Jan. 27, 1942 
Marinsky ........... July 14, 1942 
Plumley ............ Nov. 10, 1942 
FOREIGN PATENTS 
Country Date 
Great Britain ............ of 1934 
Great Britain ............ of 1939